1. Field of the Invention
The present invention relates to a guide apparatus for tubular members being inserted into a well under pressure by a snubbing unit. More particularly, the present invention relates to a guide apparatus to prevent buckling of a tubular member in the snubbing unit. Even more particularly, the present invention relates to a guide for unsupported length of a tubular member between the traveling slip bowls and the stationary slip bowls of a snubbing unit.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98.
Oil and gas fields on the ocean floor require subsea production systems for exploring, drilling, and producing under extreme environmental conditions. Subsea production systems are specialized equipment to develop these remote oil and gas fields, while being economically cost-effective and safe guarding the environment. Subsea wells present difficult problems because the wellbore is located thousands of feet from the ocean surface. The ability to erect a rig and overhead support is severely limited and expensive. The locations are remote; the equipment itself is difficult to transport and to deploy; the delivery of building and maintenance resources spans large underwater distances; and the expense of intervention can risk economic failure of an entire subsea production system.
A snubbing unit is a type of specialized equipment for oil production and well intervention. The snubbing unit or “hydraulic workover unit” or “snubbing jack” pushes tubular members, such as pipe, coiled tubing and wireline, into a well against pressure. Subsea snubbing is a heavy duty well intervention with more conventional drill pipe, instead of wireline or coiled tubing, which are other tubular members in subsea systems. The subsea location of the well requires the snubbing unit to be further specialized for withstanding the underwater conditions, such as heave compensation, and providing the force and pressure necessary to push pipe or snub into the well.
Various patents and publications disclose technology related to snubbing units and accessory devices for snubbing units.
U.S. Pat. No. 6,116,345, issued to Fontana et al on Sep. 12, 2000, discloses a prior art tubing injection system for land and underwater wells. A first injector at the wellbore on land or on the ocean floor pushes pipe or coiled tubing into the well. A second injector transfers the pipe or coiled tubing from a storage location to the first injector.
U.S. Pat. No. 6,854,520, issued to Robichaux on Feb. 15, 2005, describes a baseline prior art apparatus and method for handling a tubular. The apparatus attaches two sets of slips to a tubular member, and one set of slips can move closer or farther from the other set of slips.
United States Patent Publication No. 20070084606, published for Ponville on Apr. 19, 2007, teaches a rig assist compensation system. The snubbing jack has a base frame to compensate for heave, when the snubbing jack is on a rig. Vertical movement of the rig is balanced by base frame so that the snubbing is not disrupted. The base frame provides stability to the snubbing unit.
United States Patent Publication No. 20060078390, published for Olsen et al on Apr. 13, 2006, teaches another heave compensated snubbing system. A piston connects to the traveling slip of the snubbing unit. The piston is releasably engaged to the floating platform, so that a disengaged position allows the traveling slip to move independent from vertical movement of the floating platform.
Besides heave compensation, another problem with snubbing tubular members, such as pipe, is buckling. There is typically an unsupported length of the tubular member between the traveling slip bowls and the standing or stationary slip bowls of the snubbing unit. When the traveling slip bowls or slips push downward, this unsupported length of tubular member is in compression, and may be prone to buckling. Conventional anti-buckling guides for pipe on land are not compatible with underwater conditions and remoteness of the sea floor. Furthermore, for subsea production systems, snubbing coiled tubing, instead of more conventional pipe is desirable. Coiled tubing is even more susceptible to buckling because of the different material composition and relatively smaller diameter compared to conventional pipe. The buckling concern is a serious obstacle for snubbing coiled tubing.
United States Patent Publication No. 20120006565, published for McKinnon et al on Jan. 12, 2012, describes a pipe guide for a snubbing unit. The pipe guide has an adjustable collar to brace the pipe between the traveling slips and the stationary slips of the snubbing unit. The pipe guide has a frame that moves in coordination with the traveling slips of the snubbing jack.
It is an object of the present invention to provide a guide apparatus to prevent buckling of a tubular member snubbing into a well.
It is an object of the present invention to provide a guide apparatus to prevent buckling of a tubular member in a subsea well with a subsea snubbing unit.
It is another object of the present invention to provide a guide apparatus to prevent buckling of a tubular member between the traveling slip bowls and stationary slip bowls of a snubbing unit.
It is an object of the present invention to provide a guide apparatus for a snubbing unit to brace the unsupported length of a tubular member between the traveling slip bowls and stationary slip bowls of the snubbing unit.
It is an object of the present invention to provide a guide apparatus for a snubbing unit for use with coiled tubing.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.